Re: wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE

From: Andreas Wenk <a(dot)wenk(at)netzmeister-st-pauli(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-docs(at)postgresql(dot)org
Subject: Re: wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE
Date: 2009-08-17 10:10:29
Message-ID: 4A892C95.3000701@netzmeister-st-pauli.de
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Andreas Wenk schrieb:
> Tom Lane wrote:
>> Hmm, it would be important to keep this in sync with the core-SQL
>> description of CASE, no? (Section 9.16.1)
>
> yes. And there is written "general" form and "simple" form. I like that.
>
>> I can't say that I think "simple CASE" and "searched CASE" are good
>> descriptions of the two forms, but just switching them doesn't make it
>> much better. And doing so would likely create as much confusion as
>> it eliminates. Can we come up with some other phrases?
>
> IMO it should be the same like in 9.16.1 - a "general" form and a
> "simple" form. Then changing both sections would be ok, because in
> 9.16.1 the simple form is mentioned after the general form.
>
> Would it be correct to change it in this direction - or is this
> logically wrong (change expression to value):
>
> 38.6.2.4. Simple CASE
>
> CASE expression
> WHEN value [, value [ ... ]] THEN
> statements
> [ WHEN value [, value [ ... ]] THEN
> statements
> ... ]
> [ ELSE
> statements ]
> END CASE;
>
> Maybe it could also be value-expression ... but that I don't like that
> much.
>
> Then we could go further with this:
>
> 38.6.2.5. General CASE
>
> CASE
> WHEN boolean-expression THEN
> statements
> [ WHEN boolean-expression THEN
> statements
> ... ]
> [ ELSE
> statements ]
> END CASE;
>
> The general form of CASE provides conditional execution based on truth
> of boolean expressions. ...
>
> I think with these changes, 9.16.1 and this two sections are working
> together
>
> Cheers
>
> Andy
>
> P.S.: I can provide a patch with the changes if we discussed it and are
> willing to make a change

Hi,

before building a patch it would be nice to hear, if my approach to change the docu here
is a good one ...

Thanks

Andy

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